Hello,

Today's task was like a TypeScript puzzle. I'm working on a new feature in Waku, and I needed to create a function that only accepts specific paths. The requirements were quite specific: /foo should be valid, but not /foo/. Paths like //foo are invalid. /foo/[slug] should be recognized as valid, but it's important to differentiate it from /foo/bar. An additional challenge is to ensure that /foo/[] is considered invalid. The most complex part was handling the root path /, which seemed to require a special rule. I'm still exploring if this can be achieved without one.

My TypeScript expertise isn't super deep, but this puzzle is solvable primarily using template literals. For instance, a path like /foo/bar can be matched using /${infer X}/${infer Y}. An interesting discovery was the behavior of ${infer A}${infer B}: in this case, B can be an empty string, but A cannot. TypeScript has many such curious behaviors. To experiment and understand them better, the TypeScript Playground is an invaluable tool. If you haven't used it yet, I highly recommend giving it a try.

Happy Typing.

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